Why Do Flash Drives Cost So Much?

Alvin Pettit asks: "I wanted to get a Flash drive for my PC for the following reasons: it is quiet, I can save electricity and I don't have to worry about moving parts. When I looked for these drives I found them to be rather expensive, much more so than the smaller devices such as CompactFlash! Why do Flash drives cost so much more than CompactFlash devices?"

"I looked up IDE flash drives compared to compact flash and this is what I found:

• On pricegrabber:
  SanDisk Part# SD25B880402 880MB IDE 2.5 FLASHDRIVE is $1148.00
  This comes out to about $1.30 per meg
• Where a compact flash is
  SanDisk Part# SDCFB1000768 1 GB COMPACTFLASH CARD is $589.00
  This comes out to about $.60 per meg
• Even Ultra Compact flash is cheaper:
  SanDisk Part# SDCFH512784 512MB COMPACT FLASH ULTRA is $268.00
  This comes out to about $.52 per meg

Has anyone adapted compact flash drives to be used as bootable drives on PCs. I want to make a nice low powered quiet PC."

Comments

Data rates

[Drakon]

a 1 gig flash card is limited by your USB speeds
a 1 gig flash drive is limited by your system bus speeds

the drives are MUCH faster

Apples and Oranges.

[WasterDave]

They're not the same thing, or at least they shouldn't be. Flash memory is *really* slow, fast random access, but spectacularly slow read/write. And it wears out. A good quality flash drive should be a stack of DRAM, a battery, and some way of backing up the DRAM when the power gets yanked (and vice versa). As you can imagine, this costs a bit and since it has low demand, it is also expensive.

Dave

Re:Apples and Oranges.

[Anonymous Coward]

Flash is generally rated for one million write/erase cycles.

It's well known (and easily proven) that running a standard linux distribution from flash will swiftly destroy the media due to the way the initial boot-time 'fsck' handles drive writes.

IDE to Compact Flash and More

[MBCook]

After a quick search on google, I found this link. It's an adaptor to let you attach a Compact Flash card to a standard IDE cable (they also have one for 2.5" IDE cables. From my understanding, this should appear as a perfectly normal hard drive to your PC, so you don't need anything odd to boot off it or use it in any other was (as opposed to what you'd have to go through to use a USB Compact Flash adaptor to boot from). This one is about $20, and I know there are others.

Why do flash drives cost so much more? Most likely because they aren't easily found. They're not used much, and I'd assume that most of them have very fast access times (which is what you're paying the most for. Faster chips can be expensive as hell, but I bet there is nothing like being able to saturate your IDE channel with just one drive that you can't even hear). Of course this doesn't make a ton of sense, because to put a gig in a little CF card, the chips have to be incredibly small and dense. To put a gig of memory into something the size of a hard drive wouldn't need very dense or small chips (relitivly) and they could use more chips of lower densities so they should be able to get a decent discount.

My last comment for you is this: the ATA specification is very well documented, and RAM is cheap. If people can interface PIC chips, HC11s, FPGAs, and other things to IDE, they someone could too. I wouldn't be terribly suprised if there was a project out there somewhere (shouldn't be TOO hard to do anyway) to basically turn a bunch of RAM into an IDE drive. Then all you'd need is some sort of battery to keep it going when the PC is off. Plus it'd be easily upgradeable.

Re:IDE to Compact Flash and More

[LarryRiedel]

See also FlashMemory.com.au

Larry

Re:Speaking of compact flash

[MonMotha]

So modify the card.

Most flash chips have a pin on them you can pull high to enforce write protect. All you should have to do is connect this up and you'll have a read-only card. Of course this may require some precision soldering as most flash chips are in very small formfactors...

Compact flash has limited write cycles

[larse]

You do NOT want to use a compact flash card for a read/write file system; they have a limited number of write cycles.

Comparing Oranges to Oranges

[Nonesuch]

WasterDave writes:

They're not the same thing, or at least they shouldn't be. Flash memory is *really* slow, fast random access, but spectacularly slow read/write. And it wears out. A good quality flash drive should be a stack of DRAM, a battery, and some way of backing up the DRAM when the power gets yanked (and vice versa). As you can imagine, this costs a bit and since it has low demand, it is also expensive.

You're thinking of a RAM drive. These usually present a SCSI interface, and are really horrendously expensive. Often used to accelerate database performance on mid-range ($100K) solaris servers.

There are a number of companies selling actual "flash" drives, both as CF-to-IDE harnesses and custom packaged in a laptop-drive form factor.

These are nothing like RAM drives, and in fact are not really any more sophisticated than your standard "Compact Flash" storage card.

Here's an example with some specs:
http://www.acal.be/products/el/active/sandisk/sanc hip.htm

I have a couple of 64Mb models, you can often find them on Ebay at reasonable prices. I use them to build Diskless FreeBSD hosts.

Just remember...

[cpuwizard]

Flash memory can only be written to approx. 100,000 times in any one spot before it will fail. Flash drives (and compact flash) will try to distribute the load, but if you have anything running that is caching to the drive it can wear out quickly. So things like the tmp directory should go in RAM.